Highly efficient and broadband light transmission in 90° nanophotonic wire waveguide bends

Abstract

Nanophotonic wire silicon waveguides are indispensable components of integrated photonic circuits. Because of the inherent nature of these waveguides, such as narrow width and high-index contrast, corners with large bending radii are inevitable for efficient light transmission with small loss values, which, in turn, impedes the miniaturization of photonic components. To alleviate huge bending losses of a right angle waveguide, we designed a structure incorporating a two-dimensional (2D) photonic crystal, along with careful engineering of the individual cell at the corner. The low transmission efficiency of around 55% can be increased to 99% by implementing 2D analysis. The implementation of the computationally heavy three-dimensional finite-difference time domain method, on the other hand, produces power transmission efficiencies of approximately 52% and 92% for a regular wire bend and optimized structure, respectively. The method asserts compact size and guarantees broadband operation, which, in turn, may assist the implementation of optical interconnects to distribute effectively optical clock signals through the chip.